1. Field of the Invention
The present invention relates to wireless communication, and more particularly, to a method of processing received data in wireless communication between devices for supporting a bluetooth wireless technology. The present application is based on Korean Patent Application No. 00-17902, filed Apr. 6, 2000, which is incorporated herein by reference.
2. Description of the Related Art
A bluetooth wireless technology provided in order to remove connection cables that exist between various communication devices is an industrial standard for an ad-hoc network that is established between the various communication devices using a radio link in the 2.4 GHz band. Bluetooth wireless technology supports wireless communication at a relatively short distance between the various communication devices and provides a synchronous connection-oriented (SCO) link and an asynchronous connectionless (ACL) link.
FIG. 1 schematically shows the structure of a bluetooth wireless communication device 100. As shown in FIG. 1, in a bluetooth specification, a portion that performs wireless communication with external devices is referred to as a bluetooth module 130 or a host controller. A portion that performs a function of processing data transferred and received through the bluetooth module 130 according to an application, that is, a function which is unique to a particular type of equipment, is referred to as a bluetooth host 110. Namely, the, bluetooth module 130 transfers data to and receives data from an external device through a wireless channel. The bluetooth host 110 transfers data received from the application to the bluetooth module 130, reads data received from the bluetooth module 130, and transfers the received data to the application.
In the current bluetooth specification, a portion which defines an interface between the bluetooth host 110 and the bluetooth module 130 is called a host controller interface (HCI). In the HCI, a universal serial bus (USB) 120, a PC card, RS232, and a universal asynchronous receiver/transmitter (UART) can be used as a transport layer. FIG. 2 schematically illustrates a method of processing received data in the bluetooth HCI USB transport layer of a conventional bluetooth wireless communication device.
In the bluetooth HCI USB transport layer specification, when the bluetooth host wishes to receive data from the bluetooth module through the USB, the bluetooth host does not know whether data received from the outside through the wireless link exists in the bluetooth module. Also, according to the USB specification, the bluetooth module can transfer data to the bluetooth host only as a response to a request for data from the bluetooth host. Accordingly, the bluetooth host repeatedly requests for data by a polling method regardless of whether data received from the outside through the wireless link exists in the bluetooth module. Referring to FIG. 2, the method of processing the received data in the conventional bluetooth HCI USB transport layer will now be described.
When the bluetooth host wishes to receive data from the bluetooth module, the bluetooth host transfers an “In Packet” command (referred to as Packet-IN in FIG. 2), which is a request for data, to the bluetooth module through the USB (step 210). The types of request for data include a “Bulk-IN” request for the above-mentioned ACL link and an “Isochronous-IN” request for the SCO link.
When the data received from the outside through the wireless link exists in the bluetooth module, the bluetooth module transfers the received data to the bluetooth host through the USB (step 220) and the bluetooth host replies with a USB “ACK (Acknowledge)” with respect to the received data (step 230).
However, since the bluetooth host does not know whether data received from the outside through the wireless link exists in the bluetooth module, the bluetooth host may transfer a request for data to the bluetooth module through the USB even when no received data exists in the bluetooth module (step 240a). In this case, since no received data exists in the bluetooth module, the bluetooth module sends a “NAK (Nacknowledge)” to the bluetooth host through the USB (step 250a).
In this case, according to the current bluetooth HCI USB specification, the bluetooth host repeats a request for data until data is received from the bluetooth module (step 240b) and the bluetooth module continuously generates a “NAK” (step 250b).
Therefore, according to the current bluetooth specification, a request for data and “NAK” are repeated even when no data exists in the bluetooth module. Accordingly, an excessive overhead is generated. Namely, repeated requests for data (Bulk-IN or Isochronous-IN) from the bluetooth host use an excessive amount of bandwidth on the USB network. As a result, the total transmission speed through the entire USB is reduced and the processing speed of the bluetooth communication device is reduced.